DOC: document failing test

test/test_select.cpp

@@ -363,7 +363,7 @@ TEST_F(test_select, test_select_property_unit) {
   EXPECT_EQ(query_transaction->GetResultTable().size(), 1);
   for (const auto &row : query_transaction->GetResultTable().GetRows()) {
 
-    // TODO(tf): create bug report: this is an insertion/update problem
+    // Fails due to https://gitlab.indiscale.com/caosdb/src/caosdb-server/-/issues/264
     EXPECT_NONFATAL_FAILURE({ EXPECT_EQ(row.GetValue("TestPropDouble.unit").GetAsString(), "m"); },
                             "TestPropDouble.unit");
   }